Table of contents
1: Implementation steps of the Snake game
3. Add a black game area to the canvas
5. Define the snake data structure
6. Control the direction of the snake head
7. Put the start prompt message
8. Press the space bar to start the game
11. Implement steering function
Two: "Core Principles of Distributed Middleware and Best Practices of RocketMQ"
Show results:
1: Implementation steps of the Snake game
design game drawings
Achieve 700*800
①The width value is 700 pixels, each grid is 25 pixels, and there are 28 grids in total.
②The height value is 800 pixels, each grid is 25 pixels, and there are 32 grids in total.
1. Draw the window
Write the specific code as follows:
package demo;
import javax.swing.*;
public class MySnake {
public static void main(String[] args) {
// 创建一个窗口
JFrame frame = new JFrame();
// 指定窗口x和y的相对位置及窗口的宽度和高度值
frame.setBounds(500,25,700,800);
// 不允许拖拽改变大小
frame.setResizable(false);
// 当点击窗口关闭按钮，执行操作是退出
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
// 当前窗口显示出来
frame.setVisible(true);
}
}
The running effect is as follows:
2. Add a canvas to the window
①Create a new class MyPanel canvas and inherit JPanel at the same time. Write two methods: a no-argument construction method and an overridden drawing component, where the parameter is regarded as a brush.
② Write code in the method body: first call the parent class method to do some basic work, then set the background color, and finally add the canvas to the window of the main method.
Write the specific code as follows:
package demo;
import javax.swing.*;
import java.awt.*;
public class MyPanel extends JPanel {
public MyPanel() {
}
// 重写画组件的方法
@Override
protected void paintComponent(Graphics g) {
// 调用父类值的方法做一些基本工作
super.paintComponent(g);
// 设置背景颜色
this.setBackground(Color.red);
}
}
Add canvas in main method
The running effect is as follows:
Execution idea: When adding a canvas, execute the no-argument construction method, and then automatically execute the method of rewriting the drawing component.
3. Add a black game area to the canvas
Use the brush to fill the entire area. The four parameters are: the x coordinate in the canvas, the y coordinate in the canvas, and the width and height values.
Write the specific code as follows:
package demo;
import javax.swing.*;
import java.awt.*;
public class MyPanel extends JPanel {
public MyPanel() {
}
// 重写画组件的方法
@Override
protected void paintComponent(Graphics g) {
// 调用父类值的方法做一些基本工作
super.paintComponent(g);
// 设置背景颜色
this.setBackground(Color.red);
// 在画布中添加游戏区域（这里就和框一样大小）
g.fillRect(0,0,700,800);
}
}
The running effect is as follows:
4. Put static snake
①First of all, a static snake is composed of pictures. By default, the head points to the right; a static snake is composed of a snake head picture and two snake body pictures!
②It is mainly divided into two steps: the first step is to declare the pictures of the snake head and body; the second step is to add the declared pictures to the canvas!
Write the specific code as follows:
package demo;
import javax.swing.*;
import java.awt.*;
import java.lang.invoke.VarHandle;
public class MyPanel extends JPanel {
// 声明右侧蛇头和身体
ImageIcon right = new ImageIcon("images/right.png");
ImageIcon body = new ImageIcon("images/body.png");
public MyPanel() {
}
// 重写画组件的方法
@Override
protected void paintComponent(Graphics g) {
// 调用父类值的方法做一些基本工作
super.paintComponent(g);
// 设置背景颜色
this.setBackground(Color.red);
// 在画布中添加游戏区域
g.fillRect(0,0,700,800);
// 在画布中添加右侧蛇头和身体
right.paintIcon(this,g,100,100);
body.paintIcon(this,g,75,100);
body.paintIcon(this,g,50,100);
}
}
The running effect is as follows:
5. Define the snake data structure
When the game is running, the body of the snake will continue to grow longer, and the position of the snake will continue to change. Therefore, it is necessary to store the length and position of the snake, which is currently done using an array. The specific operation steps are as follows:
① Declare an initial value, indicating that the initial length of the snake is 3
② Declare the x-coordinate and y-coordinate of the snake. When the object is created and executes the no-argument construction method, the initialization of the snake’s right head and body position is completed. At this time, there is no need to write the code for the static snake body before, and the array is traversed by writing a loop That's it.
Write the specific code as follows:
Note: The effect of this step is the same as that of placing a static snake, but this code method is more general! For example: the initialization length is not necessarily 3, and the specific position is not necessarily at the position of 100 pixels; this encoding method is easier to maintain!
6. Control the direction of the snake head
The snake head can move up, down, left, and right. Operation steps:
① Define an enumeration direction, which has four values: up, down, left, and right, and declare three snake head pictures up, down, and left respectively.
② Declare an enumeration type variable to identify the direction of the snake head, and change the direction of the snake head by changing the value of the enumeration direction.
Define an enumeration variable to represent the direction of the snake head
package demo;
public enum Direction { // 上、下、左、右
top,bottom,left,right;
}
Declare the top, bottom, and left snake head images in the canvas
To determine the direction of the tongue by enumeration
The running effect is as follows:
7. Put the start prompt message
In the method of rewriting the drawing component, use the brush to complete it!
Write the specific code as follows:
The running effect is as follows:
8. Press the space bar to start the game
① Declare a boolean type variable isStart as false to mark the state of the game.
② Judgment, when the value of isStart is false, display the start prompt text.
③In the no-argument construction method, set the acquisition focus to true, that is, you can acquire keyboard events.
④Who will listen after getting the keyboard event, add this.addKeyListener(this); where this represents itself, but the listening event has not been processed yet; you need to implement the KeyListener interface in the MyPanel class, and rewrite three methods, namely: keyTyped(), keyPressed(), and keyReleased() can be implemented in the keyPressed() method or keyReleased() method. The parameter keyEvent indicates which key is pressed, and different numbers can be obtained by pressing different keys. Then pass e.getKeyCode() Get the number corresponding to the current key, and then judge, if you press the space bar or the number 32, the value of the current mark isStart will be reversed, and there is no prompt message to start the game, you need to call the repaint() method, which means redrawing the component.
Declare variables to mark the state of the game
Determine whether to display prompt information according to the state
In the no-argument constructor, get the focus and add a listener (implement the KeyListener class and override three methods)
Write the logic in the overridden press or pop method
When the space bar is indeed pressed, the game state is reversed and the component is redrawn!
Note: You must not write true directly, so no matter how many times you press the space bar, it will always be true, then the prompt text at the beginning will not be displayed. What we need is to click the prompt text to disappear, and press the second prompt text to display, and the cycle repeats!
9. Make the snake move
①Create a timer Timer, the first parameter is how long, for example: 100 milliseconds, the second parameter is who to look for when the time is up-this, this needs to implement the ActionListener interface, rewrite the actionPerformed() method, that is, when the time To call the actionPerformed () method.
② Start the timer in the construction method, and call the rewritten actionPerformed() method when it reaches 100 milliseconds.
③In the body of rewriting the actionPerformed() method, realize the movement of the snake; the idea of moving the snake:
If the snake moves horizontally to the right, the last body moves to the position of the previous body, that is, the x coordinate changes and the y coordinate does not change; if the snake's head also moves horizontally to the right, the x coordinate of the snake's head should be at the current position +25.
Create a timer object Timer
This implements the ActionListener interface to override the actionPerformed() method
Start the timer in the no-argument constructor
In the rewritten actionPerformed() method body, implement the snake movement logic
The running effect is as follows:
10. Implement Pause
Judging in the rewriting actionPerformed() method, when the value of the flag is true, the snake will move
When the tooltip is still there and the game has not started, it is static
When the space bar is pressed, the prompt information is not displayed and the snake starts to move horizontally to the right. The operation effect is as follows
When pressing the space bar again, the game pauses and a prompt message is displayed, and the running effect is as follows
11. Implement steering function
①Change the value of the variable direction by keyboard keys.
②In the actionPerformed() method, the snake head moves up, down, left, and right by judging the direction of the variable direction.
Specifies the direction of the snake's head according to the keyboard key pressed
Move the snake head according to the direction of the snake head
After running, press the space bar, and then press the arrow keys, the snake will move, and the running effect is as follows:
12. Add food
① Randomly generate food, declare two variables foodX and foodY to indicate the location of the food, declare a random variable random, and declare the food picture food.
②In the no-parameter construction method, generate the coordinates of food foodX and foodY
foodX = 25 + 25 * random.nextInt(20);
foodY = 25 + 25 * random.nextInt(20);
③ Add food in the paintComponect() method
Declare two variables to indicate the location of the food and declare the image of the food
Introduce the coordinates of the generated things in the no-argument construction method
add food
Results of the:
13. Eat food
When the coordinates of the snake's head and the food completely overlap, it means that the food is eaten, and the length of the snake is increased by 1, and a new food is generated; the specific implementation ideas are as follows:
①In the actionPerformed() method, if it is judged that the x coordinate of the snake head is the same as the food x coordinate foodX, and the y coordinate of the snake head is the same as the food y coordinate foodY, then add 1 to the length.
② Regenerate the x and y coordinates of the food.
Determine whether the coordinates of the snake's head and tail are consistent, which means that the food has been eaten, and the length is increased by 1, and a food is randomly generated again
The running effect is as follows:
Two: core source code
1. MySnake class
package demo;
import javax.swing.*;
public class MySnake {
public static void main(String[] args) {
// 创建一个窗口
JFrame frame = new JFrame();
// 指定窗口x和y的相对位置及窗口的宽度和高度值
frame.setBounds(500, 25, 700, 800);
// 不允许拖拽改变大小
frame.setResizable(false);
// 当点击窗口关闭按钮，执行操作是退出
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
// 添加画布
frame.add(new MyPanel());
// 当前窗口显示出来
frame.setVisible(true);
}
}
2. MyPanel class
package demo;
import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import java.lang.invoke.VarHandle;
import java.util.Random;
public class MyPanel extends JPanel implements KeyListener, ActionListener {
// 声明右侧蛇头和身体
ImageIcon right = new ImageIcon("images/right.png");
ImageIcon body = new ImageIcon("images/body.png");
// 声明上、下、左侧的蛇头图片
ImageIcon top = new ImageIcon("images/top.png");
ImageIcon bottom = new ImageIcon("images/bottom.png");
ImageIcon left = new ImageIcon("images/left.png");
// 声明两个变量表示食物的位置
int foodX;
int foodY;
// 声明一个随机数
Random random = new Random();
// 声明食物的图片
ImageIcon food = new ImageIcon("images/food.png");
// 声明一个初始值，表示蛇的长度为3
int len = 3;
// 声明两个数组分别存放蛇的x和y的坐标
int[] snakeX = new int[28 * 32]; // 最大值=宽度格子*高度格子，是蛇的最大理论长度
int[] snakeY = new int[28 * 32];
// 声明枚举变量，标识当前的蛇头方向
Direction direction = Direction.right; // 假设默认是向下
// 声明一个变量，标记游戏的状态，当为false时，表示没有开始游戏，true表示开始游戏
boolean isStart = false;
// 创建一个定时器
Timer timer = new Timer(100, this); // this必须实现ActionListener接口
public MyPanel() {
// 初始化蛇的头部和身体的初始值
snakeX[0] = 100;
snakeY[0] = 100;
snakeX[1] = 75;
snakeY[1] = 100;
snakeX[2] = 50;
snakeY[2] = 100;
// 设置获取焦点为true
this.setFocusable(true);
// 添加监听
this.addKeyListener(this); // this代表的是MyPanel，这个类要实现KeyListener类，并重写三个方法
// 启动定时器
timer.start(); // 去调用actionPerformed方法
// 生成食物foodX和foodY坐标位置
foodX = 25 + 25*random.nextInt(20);
foodY = 25 + 25*random.nextInt(20);
}
// 重写画组件的方法
@Override
protected void paintComponent(Graphics g) { // 是一个画笔
// 调用父类值的方法做一些基本工作
super.paintComponent(g);
// 设置背景颜色
this.setBackground(Color.red);
// 在画布中添加游戏区域
g.fillRect(0, 0, 700, 800);
// 在画布中添加右侧蛇头和身体
/*right.paintIcon(this,g,100,100);
body.paintIcon(this,g,75,100);
body.paintIcon(this,g,50,100);*/
// right.paintIcon(this,g,snakeX[0],snakeY[0]);
// 通过枚举变量的值来判断现在蛇头的方向
switch (direction) {
case top:
top.paintIcon(this, g, snakeX[0], snakeY[0]);
break;
case bottom:
bottom.paintIcon(this, g, snakeX[0], snakeY[0]);
break;
case left:
left.paintIcon(this, g, snakeX[0], snakeY[0]);
break;
case right:
right.paintIcon(this, g, snakeX[0], snakeY[0]);
break;
}
for (int i = 1; i < len; i++) { // 上面已经定义了蛇头，此时就要从1开始定义蛇体
body.paintIcon(this, g, snakeX[i], snakeY[i]);
}
// 放上开始提示的信息，并设置字体和颜色
if (!isStart) {
g.setColor(Color.white);
g.setFont(new Font("宋体", Font.BOLD, 50));
g.drawString("请按空格键表示游戏开始", 50, 500);
}
// 添加食物
food.paintIcon(this,g,foodX,foodY);
}
@Override
public void keyTyped(KeyEvent e) {
}
// 在此方法中编写逻辑
@Override
public void keyPressed(KeyEvent e) {// KeyEvent键盘事件
int keyCode = e.getKeyCode();
if (keyCode == 32) { // 空格键的值是32
// 游戏状态取反（一定不能直接写true）
// 写true，无论按下几次一直都是true（我们要的是按一下消失，按两下显示）
isStart = !isStart;
// 并重新画组件
repaint();
} else if (keyCode == KeyEvent.VK_UP) { // 改变蛇头的方向
direction = Direction.top;
} else if (keyCode == KeyEvent.VK_DOWN) {
direction = Direction.bottom;
} else if (keyCode == KeyEvent.VK_LEFT) {
direction = Direction.left;
} else if (keyCode == KeyEvent.VK_RIGHT) {
direction = Direction.right;
}
}
@Override
public void keyReleased(KeyEvent e) {
}
// 实现ActionListener重写的方法，在里面编写移动的逻辑
@Override
public void actionPerformed(ActionEvent e) {
if (isStart) {
// 移动身体（后一个往前移）
for (int i = len - 1; i > 0; i--) {
snakeX[i] = snakeX[i - 1];
snakeY[i] = snakeY[i - 1];
}
/* // 假如蛇头水平向右移动，则当前蛇头向前+25
snakeX[0] += 25;
// 判断，当前蛇头的值超出700，则x值从0开始
if (snakeX[0]>=700){
snakeX[0]=0;
}*/
// 根据蛇头的方向进行移动
switch (direction) {
// 向上，x轴不变，y-25
case top:
snakeY[0] -= 25;
if (snakeY[0] <= 0) {
snakeY[0] = 800;
}
break;
// 向下移，x轴不变，y+25
case bottom:
snakeY[0] += 25;
if (snakeY[0] >= 800) {
snakeY[0] = 0;
}
break;
// 向左移，y轴不变，x-25
case left:
snakeX[0] -= 25;
if (snakeX[0] <= 0) {
snakeX[0] = 700;
}
break;
// 向右移，y轴不变，x+25
case right:
snakeX[0] += 25;
if (snakeX[0] >= 700) {
snakeX[0] = 0;
}
break;
}
// 判断蛇头x和食物x的坐标是否一致，并且蛇头y和食物y坐标一致，表示吃到食物
if (snakeX[0] == foodX && snakeY[0] == foodY){
// 蛇的长度加1
len++;
// 在重新生成一个新的食物
foodX = 25 + 25*random.nextInt(20);
foodY = 25 + 25*random.nextInt(20);
}
// 重新画组件
repaint();
// 重新启动定时器
timer.start(); // 100毫秒就调用一次方法
}
}
}
3. Direction class
package demo;
public enum Direction { // 上、下、左、右
top,bottom,left,right;
}
book recommendation
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way of participation:
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How to choose version?
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brief introduction:
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